Standards for HCI
and usability are developed under the auspices of the International
Organisation for Standardisation (ISO) and the International Electrotechnical
Commission (IEC).The
status of an ISO and IEC documents is summarised in the title
of the standard:

ISO Title

Description

ISO nnnn (date)

A standard
number nnnn published on date, developed by an ISO committee.

ISO nnnn-xx (date)

Part xx
of a standard developed by an ISO committee.

ISO/IEC
nnnn (date)

A standard
developed by JTC1: a joint technical committee of ISO and
IEC.

ISO TS nnnn (date)

An ISO Technical
Specification: a normative document that may later be revised and published as a standard.

ISO TR nnnn
(date)

An ISO Technical Report: an informative document containing information
of a different kind from that normally published in a normative
standard.

ISO ZZ
nnnn (date)

A draft
standard of type ZZ made available on date.

The main stages
of development of international standards and abbreviations
(ZZ) used for the document
types are shown below:

This standard (which is part of the ISO
9241 series) provides the definition of usability that is
used in subsequent related ergonomic standards:

Usability: the extent to which a product can be used by
specified users to achieve specified goals with effectiveness,
efficiency and satisfaction in a specified context of use.

ISO 9241-11 explains how to identify the information
that it is necessary to take into account when specifying or evaluating
usability in terms of measures of user performance and satisfaction.
Guidance is given on how to describe the context of use of the
product and the measures of usability in an explicit way. It includes
an explanation of how the usability of a product can be specified
and evaluated as part of a quality system, for example one that
conforms to ISO 9001.

It also explains how measures of user performance
and satisfaction can be used to measure how any component of a
work system affects the quality of the whole work system in use.

In the software engineering community the term
usability has been more narrowly associated with user interface
design.ISO/IEC 9126, developed separately as
a software engineering standard, defined usability as one relatively
independent contribution to software quality associated with the
design and evaluation of the user interface and interaction:

Usability: a set of attributes that bear on the effort
needed for use, and on the individual assessment of such use,
by a stated or implied set of users.

ISO/IEC 9126 (1991) has recently been replaced
by a new four part standard that has reconciled the two approaches
to usability. ISO/IEC 9126-1 describes the same six categories
of software quality that are relevant during product development:
functionality, reliability, usability, efficiency, maintainability
and portability:

The definition of usability is similar:

Usability: the capability of the software product to be
understood, learned, used and attractive to the user, when used
under specified conditions.

The phrase "when used under specified conditions"
(equivalent to "context of use" in ISO 9241-11) was
added to make it clear that a product has no intrinsic usability,
only a capability to be used in a particular context.

The standard now recognises that usability plays
two roles (Bevan 1999): a detailed software
design activity (implied by the definition of usability), and
an overall goal that the software meets user needs (similar to
the ISO 9241-11 concept of usability).ISO/IEC 9126-1 uses the term "quality in use"
for this broad objective:

Quality in use: the capability of the software product
to enable specified users to achieve specified goals with effectiveness,
productivity, safety and satisfaction in specified contexts of
use.

Quality in use is the combined effect of the
six categories of software quality when the product is in use.
The overall objective is to achieve quality in use, both for the
end user and the support user.Functionality, reliability, efficiency
and usability determine quality in use for an end user in a particular
context.The support user is concerned with the
quality in use of maintenance and portability tasks.

This technical report contains examples of metrics
for effectiveness, productivity, safety and satisfaction. Specifying
usability requirements and verifying that they have been achieved
in a usability test is an important component of user centred
design (ISO 13407). ISO/IEC 9126-4 suggests metrics for effectiveness,
productivity, satisfaction and safety that can be used for this
purpose. The results can be documented using the Common
Industry Format for usability test reports, which is included
as an example in an Annex to ISO/IEC 9126-4.

A multi-part standard is being developed to specify
the information about usability that should be provided with a
consumer product, so that a purchaser can judge the ease of use
of the product. It will specify a test method, the characteristics
of a "normal user", and how to specify the characteristics
of intended users with special needs or with special skills or
experience (Bevan and Schoeffel, 2001).

These standards can be used to support user interface
development in the following ways:

1.
To specify details of the appearance and behaviour of the user
interface. ISO 14915 and IEC 61997 contain recommendations for
multi-media interfaces.More specific guidance can be found for
icons in ISO/IEC 11581, PDAs in ISO/IEC 18021 and cursor control
in ISO/IEC 10741.

3.
To provide criteria for the evaluation of user interfaces (ISO/IEC
9126 parts 2 and 3).

However the attributes that a product requires
for usability depend on the nature of the user, task and environment.
ISO 9241-11 can be used to help understand the context in which
particular attributes may be required.Usable products can be designed by incorporating product
features and attributes known to benefit users in particular contexts
of use.

ISO 9241 provides requirements and recommendations
relating to the attributes of the hardware, software and environment
that contribute to usability, and the ergonomic principles underlying
them. Parts 10 and 12 to 17 deal specifically with attributes
of the software.Parts 14-17 are intended to be used by both designers and evaluators
of user interfaces, but the focus is primarily towards the designer.

The standards provide an authoritative source
of reference, but designers without usability experience have
great difficulty applying these types of guidelines (de
Souza and Bevan 1990).To apply guidelines successfully, designers need to understand
the design goals and benefits of each guideline, the conditions
under which the guideline should be applied, the precise nature
of the proposed solution, and any procedure that must be followed
to apply the guideline.Parts 12 to 17 contain a daunting 82 pages
of guidelines, but even then do not provide all this information
for every guideline.

Several checklists have been prepared to help
assess conformance of software to the main principles in ISO 9241
(Gediga 1999, Oppermann and Reiterer 1997, Prümper 1999).

Part 10: Dialogue principles
(1996)

This part deals with general ergonomic principles
which apply to the design of dialogues between humans and information
systems: suitability for the task, suitability for learning, suitability
for individualisation, conformity with user expectations, self
descriptiveness, controllability, and error tolerance.

Part 12: Presentation of information
(1998)

This part contains recommendations for presenting
and representing information on visual displays. It includes guidance
on ways of representing complex information using alphanumeric
and graphical/symbolic codes, screen layout, and design as well
as the use of windows.

Part 13: User guidance (1998)

This part provides recommendations for the design
and evaluation of user guidance attributes of software user interfaces
including prompts, feedback, status, on-line help and error management.

Part 14: Menu dialogues (1997)

This part provides recommendations for the design
of menus used in user-computer dialogues. The recommendations
cover menu structure, navigation, option selection and execution,
and menu presentation (by various techniques including windowing,
panels, buttons, fields, etc.).

Part 15: Command dialogues
(1997)

This part provides recommendations for the design
of command languages used in user-computer dialogues. The recommendations
cover command language structure and syntax, command representations,
input and output considerations, and feedback and help.

Part 16: Direct manipulation
dialogues (1999)

This part provides recommendations for the ergonomic
design of direct manipulation dialogues, and includes the manipulation
of objects, and the design of metaphors, objects and attributes.
It covers those aspects of Graphical User Interfaces that are
directly manipulated, and not covered by other parts of ISO 9241.

Part 17: Form filling dialogues
(1998)

This part provides recommendations for the ergonomic
design of form filling dialogues. The recommendations cover form
structure and output considerations, input considerations, and
form navigation.

ISO/IEC 9126-1 defines
usability in terms of understandability, learnability, operability
and attractiveness.Parts
2 and 3 include examples of metrics for these characteristics.
These can be used to specify and evaluate detailed usability criteria.

Part 2: External metrics (DTR: 2001)

This technical report describes metrics that can
be used to specify or evaluate the behaviour of the software when
operated by the user.For
example: how long does it take to learn to use a function, can
users undo functions, do users respond appropriately to error
messages?

Part
3: Internal metrics (DTR: 2001)

This technical report describes metrics that can
be used to create requirements that that describe static properties
of the interface that can be evaluated by inspection without operating
the software. For example: what proportion of the functions are
documented, what proportion of functions can be undone, what proportion
or error messages are self explanatory?

Part 1: Icons - General (2000)

This part contains a framework for the development
and design of icons, including general requirements and recommendations
applicable to all icons.

Part 2: Object icons (2000)

This part contains requirements and recommendations
for icons that represent functions by association with an object,
and that can be moved and opened. It also contains specifications
for the function and appearance of 20 icons.

Part 3: Pointer icons (2000)

This part contains requirements and recommendations
for 8 commonly used pointer icons that represent a pointer associated
with a physical input device. It also specifies how pointer icons
change appearance to give user feedback.

Part 4: Control icons(CD: 1999)

This part contains requirements and recommendations
for 14 commonly used control icons that enable the user to operate
on windows, lists and other graphical elements.

Part 5: Tool icons(FCD: 2000)

This part contains requirements and recommendations
for 20 commonly used icons for tools, and specifies the relationships
between tool and pointer icons

Part 6: Action icons(1999)

This part contains requirements and recommendations
for 23 commonly used icons typically used on toolbars that represent
actions by association with objects that prompt the user to recall
the intended actions.

These standards can be used in the design and
evaluation of workplaces, screens, keyboards and other input devices.Unlike the software standards, most of
these standards contain explicit requirements.ISO 9241 and ISO 13406 contain requirements for visual display
terminals in offices.These
standards can be used to support adherence to European regulations
for the use of display screens (Bevan 1991).Gestures for pen-based systems are covered in ISO/IEC 14754.ISO 11064 contains ergonomic requirements for the design
of control centres.

ISO 9241 provides requirements and recommendations
relating to the attributes of the hardware, software and environment
that contribute to usability, and the ergonomic principles underlying
them. Parts 3 to 9 contain hardware design requirements and guidance.

Part 3: Visual display requirements
(1992)

This part specifies the ergonomics requirements for
display screens that ensure that they can be read comfortably,
safely and efficiently to perform office tasks. Although it deals
specifically with displays used in offices, it is appropriate
for most applications that require general-purpose displays to
be used in an office-like environment.

Part 4: Keyboard requirements
(1998)

This part specifies the ergonomics design characteristics
of an alphanumeric keyboard that may be used comfortably, safely
and efficiently to perform office tasks. Keyboard layouts are
dealt with separately in various parts of ISO/IEC 9995: Information
Processing - Keyboard Layouts for Text and Office Systems (1994).

Part 5: Workstation layout
and postural requirements (1998)

This part specifies the ergonomics requirements for
a Visual Display Terminal workplace that will allow the user to
adopt a comfortable and efficient posture.

Part 6: Guidance on the work
environment (1999)

This part provides guidance on the Visual Display
Terminal working environment (including lighting, noise, temperature,
vibration and electromagnetic fields) that will provide the user
with comfortable, safe and productive working conditions.

Part 7: Requirements for display
with reflections (1998)

This part specifies methods of measurement of glare
and reflections from the surface of display screens, including
those with surface treatments. It is aimed at display manufacturers
who wish to ensure that anti-reflection treatments do not detract
from image quality.

Part 8: Requirements for displayed
colours (1997)

This part specifies the requirements for multicolour
displays that are largely in addition to the monochrome requirements
in Part 3.

Part 9: Requirements for non-keyboard
input devices (2000)

This part specifies the ergonomics requirements for
non-keyboard input devices that may be used in conjunction with
a visual display terminal. It covers such devices as the mouse,
trackball and other pointing devices. It also includes a performance
test. It does not address voice input.

Part 6: Environmental requirements
for control rooms (WD: 2000)

Part 7: Principles for the
evaluation of control centers (WD: 2000)

Part 8: Ergonomic requirements
for specific applications (WD: 2000)

ISO/IEC 15910 provides a detailed process for
the development of user documentation (paper and on-line help),
while ISO/IEC 18019 gives more guidance on how to produce documentation
that meets user needs.

ISO/IEC
15910: Software user documentation process (1999)

This standard specifies the minimum process for creating
user documentation for software that has a user interface, including
printed documentation (e.g. user manuals and quick-reference cards),
on-line documentation, help text and on-line documentation systems.

This standard describes how to establish what information
users need, how to determine the way in which that information
should be presented to the users, and how then to prepare the
information and make it available. It covers both on-line and
printed documentation and has been developed from two British
Standards:

BS 7649: Guide to the design and preparation of documentation
for users of application software (1993)

BS 7830: Guide to the design and preparation of on-screen
documentation for users of application software (1996)

ISO 13407 explains the activities required for
user centred design, and ISO 16982 outlines the types of methods
that can be used.ISO/IEC 14598 give a general framework
for the evaluation of software products using the model in ISO/IEC
9126-1.

This standard provides guidance on human-centred
design activities throughout the life cycle of interactive computer-based
systems. It is a tool for those managing design processes and
provides guidance on sources of information and standards relevant
to the human-centred approach. It describes human-centred design
as a multidisciplinary activity, which incorporates human factors
and ergonomics knowledge and techniques with the objective of
enhancing effectiveness and efficiency, improving human working
conditions, and counteracting possible adverse effects of use
on human health, safety and performance.The recommended process is shown below:

The usability maturity model in ISO TR 18529
contains a structured set of processes derived from ISO 13407
and a survey of good practice.It can be used to assess the extent to which an organisation
is capable of carrying out user-centred design.Each HCD process (such as "specify the user and organisational
requirements") can be rated on the ISO 15504 Software Process
Assessment scale: Incomplete, Performed, Managed, Established,
Predictable or Optimising (Earthy et al, 2001).

This part introduces the multi-part standard ISO
9241 for the ergonomic requirements for the use of visual display
terminals for office tasks and explains some of the basic underlying
principles. It provides some guidance on how to use the standard
and describes how conformance to parts of ISO 9241 should be reported.

ISO 9241-2:
Part 2:Guidance on task requirements (1992)

This part deals with the design of tasks and jobs
involving work with visual display terminals. It provides guidance
on how task requirements may be identified and specified within
individual organisations and how task requirements can be incorporated
into the system design and implementation process.

This technical specification (derived from ANSI HFS
200) provides guidelines and recommendations for the design of
systems and software that will enable users with disabilities
greater accessibility to computer systems (with or without assistive
technology). It includes low vision users, hearing impaired
users, deaf users, users with physical and cognitive impairments,
and the elderly.

ISO
standards hve to be purchased. They can be obtained direct
from ISO, or from a national
standards bodyNSSN:
A National Resource for Global Standards also has a comprehensive
list of standards, some of which can be obtained electronically.In principle draft
ISO standards can also be purchased, but while the FDIS and
DIS documents published by ISO are easy to obtain, to obtain earlier
drafts (e.g. FCD, CD or DTR) the individual
secretariats have to be approached.While these early drafts may give a good
indication of the likely content of the final standard, they are
often subject to major change, and in some cases may never be
published.

Support for legislation

The European Display
Screen Equipment Directive (EEC, 1990) specifies minimum ergonomic
requirements for workstation equipment and the environment.These can be achieved by conforming to ISO 9241 parts 3-9.The Directive also requires that the "principles of
software ergonomics" are applied in designing the user interface.ISO 9241 part 10 contains appropriate
principles.The other
requirements for ease of use of software can be met by conforming
to ISO 9241 parts 12 -17.

The Machinery
Directive (EC, 1998) requires suppliers to provide machinery
that meets essential health and safety requirements, one of which
is that the interactive software is "user friendly".

The Supplier's
Directive (EEC, 1993) requires that the technical specifications
used for procurement by public bodies must make reference to relevant
standards adopted by the European standards body (CEN).These could include ergonomic and user interface standards,
provided that they have explicit conformance requirements.

European Union countries have national legislation
to implement these Directives.